Field of the Invention
The disclosure relates generally to switch-mode converters and boost devices, and more particularly it relates to switch-mode converters and boost devices utilizing a modified transistor as a bootstrap diode.
Description of the Related Art
In the application of switch-mode converters, the assistance of a one-way switching device and a capacitor is generally required to make the high-side transistor be fully conducted. FIG. 1 shows a block diagram of the high-side driving circuit of a switch-mode converter in accordance with an embodiment of the invention. As shown in FIG. 1, the high-side driving circuit 100 includes the high-side driver 101, the high-side transistor 102, the one-way switching device 104, and the capacitor 103. Since the input voltage VIN exceeds the supply voltage VS and the high-side transistor 102 is an N-type transistor, the one-way switching device 104 and the capacitor 103 are configured to boost the bootstrap voltage VB to the sum of the input voltage VIN and the supply voltage VS for keeping the high-side transistor 102 continuously conducted.
In addition, the one-way switching device 104 is not only configured to provide sufficient forward current from the supply voltage VS to the capacitor 103, but it is also configured to isolate the reverse current from the boosted bootstrap voltage VB to the supply voltage VS. Therefore, we need the one-way switching device 104 to be efficient and able to be integrated into the integrated circuit for improving the efficiency of circuits and reducing the cost of production.